1. Technical Field
The present invention relates to polypropylene resin compositions and injection-molded articles made of the polypropylene resin compositions. Particularly, the invention relates to polypropylene resin compositions which are capable of affording molded articles superior in impact resistance and appearance and, in particular, which hardly suffer from occurrence of flow marks when being molded. The invention also relates to injection-molded articles made of such polypropylene resin compositions.
2. Description of the Related Art
Polypropylene resin has been used as a material of automotive parts. For instance, JP-A-8-59953, also published as EP 0 669 372 A1, discloses a polypropylene resin composition for automotive interior parts, the composition comprising a propylene-ethylene block copolymer comprising a propylene-ethylene random copolymer portion having an average intrinsic viscosity [η] of 7 to 12 dl/g and an inorganic filler, the composition being superior in balance between rigidity and low-temperature brittle temperature and also being superior in fluidity.
In JP-A-2002-12718, also published as US 2002/0004546 A1, and JP-A-2003-128855, also published as US 2003/0100664 A1, disclosed as a thermoplastic resin composition which is superior in rigidity, impact strength and fluidity and which is capable of affording molded articles with good appearance is a thermoplastic resin composition containing a polypropylene resin, an elastomer, an inorganic filler and a resin having a melt tension within a specific range and a swelling ratio within a specific range and needing a time within a specific range until its relaxation modulus ratio reaches 0.01, wherein the content of the elastomer is from 10 to 35% by weight.
Molded articles, in particular, materials for automobiles have recently been required to have a superior impact resistance. For instance, molded articles made of the resin compositions disclosed in the above-cited publications have been required to have an improved impact resistance.